Process for preparing unsaturated acids with Mo, V, Ti-containing catalysts

ABSTRACT

A novel catalyst comprising the elements Mo, V and Ti, and an oxidation process, is provided for oxidizing alpha beta unsaturated aliphatic aldehydes in the vapor phase with molecular oxygen to produce the corresponding alpha-beta unsaturated carboxylic acid.

This is a continuation-in-part of Ser. No. 408,416 filed Oct. 23, 1973,abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the vapor phase catalytic oxidation ofunsaturated aliphatic aldehydes to the corresponding unsaturatedaliphatic carboxylic acid.

2. Description of the Prior Art

The use of molybdenum and vanadium containing catalyst systems for thegas phase oxidation of alpha-beta unsaturated aliphatic aldehydes, suchas acrolein, to the corresponding alpha-beta-unsaturated carboxylicacids, such as acrylic acid, has been known.

In these reactions a gaseous reaction mixture which usually contains thealdehyde, molecular oxygen and water, as steam, is brought into contactwith the catalyst, by continuously passing a stream of the reactionmixture through a bed of the catalyst. Such known catalyst systems wouldinclude those disclosed in the following U.S. Pat. Nos.: 3,087,964;3,358,020; 3,408,392; 3,435,069; 3,439,028; 3,530,175; 3,567,772;3,567,773; 3,574,729; 3,644,509; 3,655,749; 3,670,017 and 3,703,548. Notall of these catalyst systems, however, are currently useful forcommercial purposes. Some of these catalyst systems, for example, do notprovide the relatively high levels of % conversion, productivity and %selectivity, which are all required, presently, of a commercially usefulcatalyst system.

The terms % conversion, productivity, and % selectivity which areemployed herein with respect to the present invention are defined asfollows: ##EQU1## wherein A is as defined above in equation Ia.

SUMMARY OF THE INVENTION

Alpha-beta-unsaturated aliphatic carboxylic acids are produced with arelatively high % conversion, productivity and % selectivity byoxidizing the corresponding alpha-beta-unsaturated aldehyde in the vaporphase by contacting the aldehyde, in the presence of molecular oxygenand steam, with certain catalyst compositions containing molybdenum,vanadium and titanium.

An object of the present invention is to provide novel catalystcompositions for the vapor phase oxidation of alpha-beta-unsaturatedaliphatic aldehydes to the corresponding alpha-beta-unsaturatedaliphatic carboxylic acid.

A further object of the present invention is to provide a processwhereby alpha-beta-unsaturated aliphatic aldehydes can be oxidized inthe gas phase so to produce the corresponding alpha-beta unsaturatedaliphatic carboxylic acid with a relatively high level of % conversion,productivity and % selectivity.

These and other objects of the present invention are achieved by usingas such a catalyst in such a process a composition comprising theelements Mo, V, Ti and X in the ratio

    Mo.sub.a V.sub.b Ti.sub.c X.sub.d

wherein X is Fe, Cu, Co, Cr, and/or Mn

a is 12,

b is 1 to 14, and preferably 2 to 8,

c is 0.1 to 12, and preferably 0.5 to 2, and

d is 0 to 3.0, and preferably 0.01 to 1.0.

The numerical values of a, b, c and d represent the relative atom-moleratios of the elements Mo, V, Ti, and X, respectively, which are presentin the catalyst composition.

THE CATALYST

The elements Mo, V, Ti, and X present in the catalyst composition incombination with oxygen in the form, it is believed, of various metaloxides.

The catalyst is preferably prepared from a solution of soluble saltsand/or complexes and/or compounds of each of the metals Mo, V, Ti and X.The solution is preferably an aqueous system having a pH of 1-12, andpreferably 5±3, at a temperature of about 20° to 100° C. The solution ofthe metal containing compounds is prepared by dissolving sufficientquantities of soluble compounds of each of the metals, so as to providethe desired a:b:c:d atom-mole ratios of the elements Mo, V, Ti and X,respectively. The selected salts, complexes or compounds of the metalsMo, V and Ti should be mutually soluble. If the selected salts,complexes or compounds of the metal X are not mutually soluble with theother compounds, they can be added last to the solution system. Thecatalyst composition is then prepared by removing the water or othersolvent from the mixture of the metal compounds in the solution system.Any portion, and preferably i.e. about <50 weight %, of the titanium maybe replaced by tantalum and/or niobium in the catalyst composition.

The water or other solvent can be removed from the mixture of thedissolved metal compounds by evaporation.

Where the catalyst is to be used on a support, the metal compounds aredeposited on a porous support usually having a surface area of about0.01 to 2 square meters per gram. The support has an apparent porosityof 30-60%; at least 90% of the pores have a pore diameter in the rangeof 20-1500 microns. The support is usually used in the form of particlesor pellets which are about 1/8 to 5/16 inch in diameter. The depositionis accomplished by immersing the support in the solution and thenevaporating off the major portion of the solvent, and then drying thesystem at about 80° to 140° C. for 2 to 60 hours. The dried catalyst isthen calcined by being heated at 250° to 450° C., and preferably325°-425° C., for 2 to 24 hours in air to produce the desired

    Mo.sub.a V.sub.b Ti.sub.c X.sub.d

composition.

When used on the support, the supported oxides usually comprise about 10to 50 weight % of the total catalyst composition; of the total catalystcomposition about 50 to 90 weight % is support.

The molybdenum is preferably introduced into solution in the form ofammonium salts thereof such as ammonium paramolybdate, and organic acidsalts of molybdenum such as acetates, oxalates, mandelates andglycolates. Other water soluble molybdenum compounds which may be usedare partially water soluble molybdenum oxides, molybdic acid, and thenitrates and chlorides of molybdenum.

The vanadium is preferably introduced into solution in the form ofammonium salts thereof such as ammonium meta-vanadate and ammoniumdecavanadate, and organic acid salts of vanadium such as acetates,oxalates and tartrates. Other water soluble vanadium compounds which maybe used are partially water soluble vanadium oxides, and the sulfatesand nitrates of vanadium.

The titanium is preferably introduced into solution in the form of awater soluble chelate coordinated with ammonium lactate. Other solubletitanium compounds which may be used are those in which titanium iscoordinated, bonded, or complexed to a beta-diketonate, a carboxylicacid, an amine, an alcohol or an alkanolamine.

Where tantalum and/or niobium are used for a portion of the titanium,they are preferably introduced into solution in the form of oxalates.Other sources of soluble tantalum and niobium which may be used aretantalum and niobium compounds in which the tantalum or niobium iscoordinated, bonded, or complexed to a beta-diketonate, a carboxylicacid, an amine, an alcohol or an alkanolamine.

The iron, copper, cobalt, chromium and manganese are preferablyintroduced into solution in the form of nitrates. Other water solublecompounds of these elements which may be used are the water solublechlorides and organic acid salts such as the acetates, oxalates,tartrates, lactates, salicylates, formates and carbonates of suchmetals.

It is believed that, for the catalysts to be most effective, the Mo, V,Ti, X metal components should be reduced below their highest possibleoxidation states. This may be accomplished during the thermal treatmentof the catalyst in the presence of reducing agents such as NH₃ ororganic reducing agents, such as the organic complexing agents, whichare introduced into the solution systems from which the catalysts areprepared. The catalyst may also be reduced in the reactors in which theoxidation reaction is to be conducted by the passage of hydrocarbonreducing agents such as propylene through the catalyst bed.

THE ALDEHYDES

The alpha-beta-unsaturated aldehydes which are oxidized in the processof the present invention have the structure ##STR1##

wherein R₁ is H or a C₁ -C₆ alkyl radical and R₂ and R₃ are the same ordifferent and are H or CH₃.

These aldehydes thus include acrolein and methacrolein. Where acroleinand/or methacrolein are oxidized, the correspondingalpha-beta-unsaturated carboxylic acid would be acrylic acid and/ormethacrylic acid, respectively.

The aldehydes may be oxidized individually or in combinations thereof.

THE REACTION MIXTURE

The components of the reaction mixture which are employed in the processof the present invention, and the relative ratios of the components insuch mixtures, are the following

1 mole of aldehyde,

0.2 to 5 moles of molecular oxygen (as pure oxygen or in the form ofair),

1 to 25 moles of water (in the form of steam), and

optionally, 0.1 to 5 moles of alpha-beta-unsaturated olefin having thesame number of carbon atoms as the aldehyde being oxidized. Propylene,for example, can be used in the reaction mixture when acrolein is beingoxidized to acrylic acid.

The water, or steam, can be used as a reaction diluent and as a heatmoderator for the reaction. Other diluents which may be used are inertgases such as nitrogen, CO₂ and gaseous saturated hydrocarbons.

The olefin may be present due to the fact that the aldehyde feed may beemanating as the effluent from an olefin→aldehyde oxidation reactionprocess, and such effluent usually contains unreacted olefin.

The components of the reaction mixture are uniformly admixed prior tobeing introduced into the reaction zone. The components are preheated,individually or after being admixed, prior to their being introducedinto the reaction zone, to a temperature of about 200° to 300° C.

REACTION CONDITIONS

The preheated reaction mixture is brought into contact with the catalystcomposition, in the reaction zone, under the following conditions:

pressure of about 1 to 10, and preferably of about 1 to 3 atmospheres,

temperature of about 200° to 400° C., and preferably of about 250° to350° C.,

contact time (reaction mixture on catalyst) of about 0.1 to 10, andpreferably of about 1 to 3, seconds, and a space velocity of about 1000to 6000 h⁻¹, preferably 4000 to 5000 h⁻¹.

The contact time may also be defined as the ratio between the apparentvolume of the catalyst bed and the volume of the gaseous reactionmixture fed to the catalyst bed under the given reaction conditions in aunit of time.

The reaction pressure is initially provided by the feed of gaseousreactants and diluents, and after the reaction is commenced, thepressure is maintained, preferably, by the use of suitable backpressurecontrollers placed on the gaseous effluent side of the catalyst bed.

The reaction temperature is preferably provided by placing the catalystbed within a tubular converter whose walls are immersed in a suitableheat transfer medium, such as tetralin, molten salt mixtures, or othersuitable heat transfer agent, which is heated to the desired reactiontemperature.

The following examples are merely illustrative of the present inventionand are not intended as a limitation upon the scope thereof.

The examples provided below disclose the preparation of various catalystcompositions, and the use of such compositions in the oxidation ofacrolein to acrylic acid.

The activity of each experimental catalyst was determined in a jacketedone-inch stainless steel reactor or converter tube 78 inches long. Thejacket contained tetralin which served as a heat transfer medium.

The center portion (55 inches) of the reactor tube was charged with 800ml of catalyst with a one-eighth inch movable thermocouple in thecatalyst bed.

The catalysts were tested at 30 psig, with a space velocity of 4600 hr⁻¹or contact time of 1.2 seconds, and an inlet feed composed of 3 mole %acrolein, 6 mole % oxygen, 15 mole % steam, and 76 mole % nitrogen.

The activity of the catalysts was tested by adjusting the temperature ofthe reactor tube jacket to produce a maximum temperature (hot spot) of304°-306° C. in the catalyst bed, while the oxidation reaction wasoccurring.

Space velocity is calculated by determining the total reactor outlet gasequivalents (in liters) of the total effluent evolved over a period ofone hour. This room temperature volume is converted to the volume at 0°C. at 760 mm Hg. ##EQU2##

EXAMPLE 1

    Mo.sub.2.4 V.sub.0.6 Ti0.3Fe.sub.0.15 or Mo.sub.12.0 V.sub.3.0 Ti.sub.1.5 Fe.sub.0.75

Seventy grams of ammonium meta-vanadate (0.6 grams atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 175 grams of titanium ammoniumlactate (chelate) solution (containing 0.3 gram atoms Ti) and 60 gramsof ferric nitrate [Fe(NO₃)₃.9H₂ O] (0.15 gram atoms Fe) dissolved in100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 27.2 weight %. Catalytic test results for thismaterial are given in Table I.

EXAMPLE 2

    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cu.sub.0.15

Seventy grams of ammonium meta-vanadate (0.6 grams atoms of V) and 424grams of ammonium paramolybdate (2.4 grams atoms of Mo) were dissolvedin two liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 175 grams of titanium ammoniumlactate (chelate) solution (containing 0.3 gram atoms Ti) and 36 gramsof copper nitrate [Cu(NO₃)₃.3H₂ O] (0.15 gram atoms Cu) dissolved in100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained, is 28.6 weight %. Catalytic test results for thismaterial are given in Table I.

EXAMPLE 3

    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Mn.sub.0.15

Seventy grams of ammonium meta-vanadate (0.6 gram atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C., in a stainless steelbeaker.

To the resulting solution was added 175 grams of titanium ammoniumlactate (chelate) solution (containing 0.3 gram atoms Ti) and 54 gramsof 50.3% manganese nitrate solution (0.15 gram atoms Mn) dissolved in100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 27.8 weight %. Catalytic test results for thismaterial are given in Table I.

EXAMPLE 4

    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cr.sub.0.15

Seventy grams of ammonium meta-vanadate (0.6 gram atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 175 grams of titanium ammoniumlactate (chelate) solution (containing 0.3 gram atoms Ti) and 60 gramsof chromium nitrate [Cr(NO₃).9H₂ O] (0.15 gram atoms Cr) dissolved in100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 26.1 weight percent. Catalytic test results forthis material are given in Table I.

EXAMPLE 5

    Mo.sub.2.8 V.sub.0.7 Ti.sub.0.35

Eighty-two grams of ammonium meta-vanadate (0.7 gram atoms of V) and 494grams of ammonium paramolybdate (2.8 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 204 grams of titanium ammoniumlactate (chelate) solution (containing 0.35 gram atoms Ti) and 28 gramsof ammonium nitrate (NH₄ NO₃) (0.35 gram moles NH₄ NO₃) dissolved in100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 30.4 weight %. Catalytic test results for thismaterial are given in Table I.

EXAMPLE 6

    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cu.sub.0.15 made with (NH.sub.4 OH).sub.0.5

Seventy grams of ammonium meta-vanadate (0.6 gram atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 175 grams of titanium ammoniumlactate (chelate) solution containing 0.3 gram atoms of Ti and 18 gramsof ammonium hydroxide containing 28.6% NH₃ (0.15 gram moles NH₃) plus 36grams of copper nitrate [Cu(NO₃)₂.3H₂ O] (0.15 gram atoms Cu) dissolvedin 100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 27.8 weight %. Catalytic test results for thismaterial are given in Table I.

EXAMPLE 7

    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Co.sub.0.15

Seventy grams of ammonium meta-vanadate (0.6 gram atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 175 grams of titanium ammoniumlactate (chelate) solution (containing 0.3 gram atoms Ti) and 44 gramsof cobalt nitrate [Co(NO₃)₂.6H₂ O] (0.15 grams atoms Co) dissolved in100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 27.1 weight %.

EXAMPLE 8

    Mo.sub.2.8 V.sub.0.7 Ti.sub.0.175 Cu.sub.0.175

Eighty-two grams of ammonium meta-vanadate (0.7 gram atoms of V) and 495grams of ammonium paramolybdate (2.8 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 102 grams of titanium ammoniumlactate (chelate) solution (containing 0.175 gram atoms Ti) and 42 gramsof copper nitrate [Cu(NO₃)₂.3H₂ O] (0.175 gram atoms Cu) dissolved in100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 29.2 weight percent. Catalytic test results forthis material are given in Table I.

EXAMPLE 9

    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cu.sub.0.15

Seventy grams of ammonium meta-vanadate(0.6 gram atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution was added a solution containing 84 grams oftitanium hydrate pulp (0.3 gram atoms Ti) 54 grams of ammonium lactate(0.6 moles ammonium lactate) and 40 grams 28.6% aqueous ammoniumhydroxide (0.67 moles ammonium ion). 36 grams cupric nitrate (0.15 gramatoms Cu) in 100 ml water was then added.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina(#SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 25.8 weight %. Catalytic test results for thismaterial are given in Table I.

EXAMPLE 10

    Mo.sub.2.4 V.sub.0.6 Fe.sub.0.15

Seventy grams of ammonium meta-vanadate (0.6 grams atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 60 grams ferric nitrate[Fe(NO₃)₃.9H₂ O] (0.15 gram atoms Fe) dissolved in 100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 27.5 weight percent. Catalytic test results forthis material are given in Table I.

EXAMPLE 11

    Mo.sub.2.4 V.sub.0.6 Fe.sub.0.15 made with 0.75 (mole) parts (NH.sub.4).sub.2 oxalate

Seventy grams of ammonium meta-vanadate (0.6 gram atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 107 grams of ammonium oxalate[(NH₄)₂ C₂ O₄.H₂ O] (0.75 gram moles (NH₄)₂ C₂ O₄) and 60 grams offerric nitrate [Fe(NO₃)₃.9H₂ O] (0.15 gram atoms Fe) dissolved in 100-mlwater.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina(#SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 26.3 weight percent. Catalytic test results forthis material are given in Table I.

EXAMPLE 12

    Mo.sub.2.8 V.sub.0.7

Eighty-two grams of ammonium meta-vanadate (0.7 gram atoms of V) and 256grams of oxalic acid (2.1 moles) were dissolved in two liters of waterwhile stirring at 60°-80° C. in a stainless steel beaker.

To the resulting solution were added 495 grams of ammonium paramolybdate(2.8 gram atoms Mo) dissolved in 1 liter of water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina(#SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 26.5 weight %. Catalytic test results for thismaterial are given in Table I.

EXAMPLE 13

    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cu.sub.0.15

Seventy grams of ammonium meta-vanadate (0.6 gram atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 84 grams of titanium hydrate pulp(0.3 gram atoms Ti) 39 grams of 28.6% ammonium hydroxide solution (0.67moles ammonium ion) and 36 grams of cupric nitrate (0.15 gram atoms Cu).

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina(#SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 26.0 weight percent. Catalytic test results forthis material are given in Table I.

EXAMPLE 14

    Mo.sub.2.4 V.sub.0.6 Cu.sub.0.15

Seventy grams of ammonium meta-vanadate (0.6 gram atoms of V) and 424grams of ammonium paramolybdate (2.4 gram atoms of Mo) were dissolved intwo liters of water while stirring at 60°-80° C. in a stainless steelbeaker.

To the resulting solution were added 90 grams of ammonium lactatesolution (containing 0.6 gram nole NH₄ lactate) and 36 grams of coppernitrate [Cu(NO₃)₂.3H₂ O] (0.15 gram atoms Cu) dissolved in 100-ml water.

The resulting mixture was heated while stirring and approximately 60percent of the water was evaporated off.

The resulting concentrated slurry was transferred to a stainless steelevaporating dish and 1040 grams (1000 ml) Norton silica-alumina (No.SA-5218) 1/4" spheres were added. This was followed by drying byevaporation with stirring on a steam bath. Further drying was carriedout at a temperature of 120° C. for a period of 16 hours.

The dried material was then transferred to a tray fabricated from10-mesh stainless steel wire screen and calcined in a muffle furnace for5 hours at 400° C. in an ambient atmosphere of air. The amount ofcatalyst deposited on the support calculated from the weight increase ofthe catalyst obtained is 26.0 weight %. Catalytic test results for thismaterial are given in Table I.

The support used in the examples was essentially an (˜86/14) Al₂ O₃/SiO₂ material having an apparent porosity of 36-42% and a surface areaof <1 m² /gram. About 100% of the pores in the support had a porediameter of about 20-180.

The pH of the solutions used in each of the examples for the preparationof the catalysts was in the range of 5±3.

The results of Examples 1 to 8 reported below in Table I demonstratethat when the catalyst compositions are prepared in accordance with theteachings of the present invention, as described above, the resultingcatalysts provide a combination of relatively high levels of %conversion, productivity and % selectivity in the oxidation ofalpha-beta-unsaturated aldehydes such as acrolein to the correspondingalpha-beta-unsaturated acid.

The results of Examples 9 to 14 reported below in Table I demonstratethat not all compositions containing the elements Mo, V and X, asdefined above, provide catalysts which can be used in the oxidation ofalpha-beta unsaturated aldehydes such as acrolein to produce thecorresponding alpha-beta unsaturated acid at relatively high levels of %conversion, productivity and % selectivity.

                                      TABLE I                                     __________________________________________________________________________                        Metal*                                                         Catalyst Description                                                                         Oxides in                                                                           Hot Spot                                                                           Conversion,                                                                          AA/Ft.sup.3 Cat./                                                                    Efficiency                       Example                                                                            Atomic Ratios  Catalyst %                                                                          °C.                                                                         %      hr. Lbs.                                                                             %                                __________________________________________________________________________    1    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Fe.sub.0.15                                                  27.2  304  86.2   22.71  89.3                             2    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cu.sub.0.15                                                  28.6  305  92.4   24.62  91.2                             3    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Mn.sub.0.15                                                  27.8  306  90.6   22.94  89.3                             4    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cr.sub.0.15                                                  26.1  305  55.0   14.11  89.3                             5    Mo.sub.2.8 V.sub.0.7 Ti.sub.0.35                                                         (a) 30.4  304  92.3   21.35  84.2                             6    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cu.sub.0.15                                              (b) 27.8  305  90.6   21.60  91.0                             7    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Co.sub.0.15                                                  27.1  308  90.7   21.80  87.0                             8    Mo.sub.2.8 V.sub.0.7 Ti.sub.0.175 Cu.sub.0.175                                               29.2  306  81.1   20.00  89.6                             9    Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cu.sub.0.15                                              (a), (c)                                                                          25.8  305  52.7   11.30  81.9                             10   Mo.sub.2.4 V.sub.0.6 Fe.sub.0.15                                                             27.5  305  13.4   2.20   58.0                             11   Mo.sub.2.4 V.sub.0.6 Fe.sub.0.15                                                         (d) 26.3  318  20.3   3.10   50.9                             12   Mo.sub.2.8 V.sub.0.7                                                                     (a) 26.5  305   7.7   1.40   62.9                             13   Mo.sub.2.4 V.sub.0.6 Ti.sub.0.3 Cu.sub.0.15                                              (c), (f)                                                                          26.0  305  16.7   2.40   50.8                             14   Mo.sub.2.4 V.sub.0.6 Cu.sub.0.15                                                         (g) 26.0  305  30.4   7.40   83.9                             __________________________________________________________________________     AA = acrylic acid                                                             (a) Used 0.35 (mole) parts ammonium nitrate.                                  (b) Used 0.15 (mole) parts ammonium hydroxide.                                (c) Used titanium hydrate pulp.                                               (d) Used 0.75 (mole) parts ammonium oxalate.                                  (e) Used 2.1 (mole) parts oxalic acid.                                        (f) Used 0.67 (mole) parts ammonium hydroxide.                                (g) Used 0.60 (mole) parts ammonium hydroxide.                                *Oxides of the metals Mo, V, Ti, and/or X.                               

What is claimed is:
 1. A process for the production of unsaturatedaliphatic carboxylic acid by vapor phase catalytic oxidation of thecorresponding unsaturated aliphatic aldehyde with molecular oxygen inthe presence of steam, said aldehyde having the structure ##STR2##wherein R₁ is H or a C₁ to C₆ alkyl radical and R₂ and R₃ are the sameor different and are H or CH₃, which comprises contacting the reactionmixture with a catalytically effective amount of a calcined oxidationcatalyst consisting essentially of the elements Mo, V, Ti, and X in theratio

    Mo.sub.a V.sub.b Ti.sub.c X.sub.d

wherein X is selected from the group consisting of Fe, Cu, Co, Cr,and/or Mn a is 12, b is 1 to 14 c is 0.1 to 12, and d is 0.01 to 1.0. 2.A process as in claim 1 in which said unsaturated aliphatic acid isacrylic acid and said unsaturated aliphatic aldehyde is acrolein.
 3. Aprocess as in claim 2 in which said oxidation catalyst is supported onan inert support.
 4. A process as in claim 3 in which said support issilica, alumina, or silica-alumina.
 5. A process as in claim 1 in whicha is 12, b is 2 to 8, c is 0.5 to 2 and d is 0.01 to 1.0.
 6. A processas in claim 5 in which X comprises Fe.
 7. A process as in claim 5 inwhich X comprises Cu.
 8. A process as in claim 5 in which X comprisesCo.
 9. A process as in claim 5 in which X comprises Cr.
 10. A process asin claim 5 in which X comprises Mn.
 11. A process for the preparation ofan unsaturated aliphatic carboxylic acid by vapor phase catalyticoxidation of the corresponding unsaturated aldehyde having the structure##STR3## wherein R₁ is H or a C₁ to C₆ alkyl radical and R₂ and R₃ arethe same or different and are H or CH₃, with molecular oxygen in thepresence of steam and a solid catalyst at a temperature of between about220° to 400° C. with a contact time of about 0.1 to 10 seconds, whereinsaid catalyst consists essentially of the elements Mo, V, Ti and Cr incombination with oxygen and having the empirical formula:

    Mo.sub.12 V.sub.b Ti.sub.c Cr.sub.d

wherein b is 1 to 14, c is 0.1 to 12, d is 0.01 to 1.0.
 12. A process asin claim 11 in which said unsaturated aliphatic carboxylic acid isacrylic acid and said unsaturated aliphatic aldehyde is acrolein.
 13. Aprocess for the production of an unsaturated aliphatic carboxylic acidby the vapor phase catalytic oxidation with molecular oxygen of thecorresponding aliphatic aldehyde having the structure: ##STR4## whereinR₁ is hydrogen or a C₁ to C₆ alkyl radical and R₂ and R₃ are the same ordifferent and are H or CH₃, which comprises contacting said molecularoxygen and unsaturated aldehyde in the presence of steam with acatalytically effective amount of an oxidation catalyst consistingessentially of the elements Mo, V, Ti, Fe, and Y in combination withoxygen and having the empirical formula:

    Mo.sub.a V.sub.b Ti.sub.c Fe.sub.d Y.sub.e

wherein Y is selected from the group consisting of Co, Cr, and/or Mn, ais 12, b is 1 to 14, c is 0.1 to 12, d is a number greater than 0 and upto 3, e is 0 to 3 with the proviso that d+e is3or less; said catalystshaving been prepared by drying an aqueous slurry or solution of salts ofsaid elements followed by calcination.
 14. A process as in claim 13 inwhich said unsaturated aliphatic acid is acrylic acid and saidunsaturated aliphatic aldehyde is acrolein.
 15. A process as in claim 14in which said oxidation catalyst is supported on an inert support.
 16. Aprocess as in claim 15 in which said support is silica, alumina, orsilica-alumina.
 17. A process as in claim 16 in which a is 12, b is 2 to8, c is 0.5 to 2, d is 0.01 to 1.0 and e is 0 to 3 with the proviso thatd+e is 3 or less.
 18. A process as in claim 13 in which Y comprises Co.19. A process as in claim 13 in which Y comprises Cr.
 20. A process asin claim 13 in which Y comprises Mn.